1. Field of the Invention
The present invention relates to methods and systems for modeling heat transfer within data processing systems.
2. Description of the Related Art
Large computer systems are often consolidated into centralized data centers, which can be less problematic and expensive than separately administering a multitude of scattered smaller servers. Rack systems, for example, conserve space and put the servers and infrastructure within easy reach of an administrator. For example, some of the more compact server arrangements currently available include blade servers. A blade server, such as the IBM eServer BLADECENTER (IBM and BLADECENTER are registered trademarks of International Business Machines Corporation, Armonk, N.Y.), is a type of rack-optimized server that eliminates many of the complications of previous generation rack servers. Blade server designs range from ultra-dense, low-voltage, lesser-performing severs to high performance, lower density servers to proprietary, customized solutions that include some blade features.
Due to the compact nature of rack systems, individual servers share a thermal profile with other hardware, such as enclosures, power supplies, fans and management hardware. Monitoring and managing power consumption and cooling is therefore critical. Because of the large number of elements typically housed within rack systems, the airflow and heating patterns are fairly complicated. Many possible sources of thermal problems can exist, exacerbating the detrimental effects of failures and complicating maintenance procedures.
U.S. Pat. No. 6,889,908 decribes a technique for diagnosing thermal anomalies in electronic equipment by introducing fault scenarios into a Flow Network Model of the equipment, and determining which fault predicts a set of expected temperatures that match observed temperatures. Some embodiments receive temperature readings associated with elements of a system. The temperature readings are dependent upon airflow and heating patterns of the elements. Differences between the temperature readings and expected temperatures are detected. Potential airflow and heating patterns associated with a thermal problem are then identified. Some embodiments, in particular, collect temperature readings from temperature sensors within an enclosure of the system and select a failure scenario associated with a root cause of thermal problem that is similar to the thermal problem described by the temperature readings collected.
Recirculation of heated air is another issue rack mounted equipment. Rack systems typically house a number of elements having interrelated airflow and heating patterns. Recirculation can be induced in open areas between the rack-mounted equipment, such as in and around empty slots. Ideally, these rack openings are blocked off by bolting blank filler panels to the rack frame. If the blank filler panels are left off, however, the pressure difference created by fans within the rack mounted equipment can force heated exhaust air to travel forward through the rack via a missing panel to the front of the equipment, where it is sucked back in. Another way heated air may recirculate is if the rack is placed near a wall, such that air vented from the back of the rack is deflected or channeled back towards the front.
Recirculation of warm air can cause rack mounted equipment to experience a substantial temperature increase. The additional heat introduced to the equipment by recirculating warm air may cause the equipment to exceed thermal thresholds, particularly if the equipment is operating in a room that is very warm to begin with, or if the amount of heating that takes place within the equipment is substantial. These high temperatures can cause the equipment to shut down or require it to be removed from services. Some portions of rack mounted equipment may experience more recirculation than others, which may interfere with the proper diagnosis of thermal problems. The difference between ambient room temperature air and heated air exiting from the back of rack mounted equipment can easily be 20 to 30° C. or more. If some of this exhaust air re-enters the equipment, it can cause the equipment to run warmer.
Therefore, there remains a need for an improved system and method for thermal analysis within a data processing system such as a rack enclosure. It would be desirable for the system nd method to more fully account for recirculation of air, thereby improving the reliability and effectiveness of operating the rack enclosure or other data processing system.